Antisocial behavior in youth is a growing problem in our society. Childhood antisocial behaviors (e.g., conduct problems) can become chronic as reflected in delinquency, adult interpersonal and domestic violence and other criminal behavior. A pattern of chronic child, adolescent and adult antisocial behavior weighs heavily on society with respect to the high cost of treatment, pain and suffering for the victims and their family, and even loss of lives. The majority of studies of antisocial behavior have focused on individual psychological factors, or peer and neighborhood influence. Few studies considered physiological aspects of antisocial behavior in children, in spite of the growing evidence linking physiological processes and crime in adults. The aims of the study are: (1) To examine the relationship between gonadal and adrenal hormone concentrations and conduct problems in children, (2) To examine whether gonadal and adrenal hormones moderate the effect of treatment on conduct problems, and (3) To examine whether treatment of conduct problems alters gonadal and adrenal hormones of children with conduct problems. In response to the NINR RFA, "Clinical Trials: Collaborations for Nursing Research," encouraging a link with an existing clinical trial, we will take advantage of a unique opportunity to assess the effect of a behavior intervention on hormone concentrations in a treatment trial to reduce severe conduct problems in sample of 6 to 11-year-old boys and girls (N = 158). There is random assignment to treatment conducted in either the experimental (EXP) community setting (home, school, neighborhood) or the clinic (CLIN). Services are provided by trained clinicians who administer specialized treatment protocols that address problems across participants (child, parent, teachers) and contexts (home, community). A comparison group for treatment as usual (TAU) in a community mental health center also will be included. Our proposed methodology of adding hormones enhances the field by addressing limitations of the few previous studies of children and conduct problems utilizing physiological measures. We anticipate that findings will contribute to further understanding of the neurophysiology of conduct problems in youth. The project is unique in that it is longitudinal and it examines for the first time, the effect of behavioral interventions on physiological processes.